Interleukin-1 alpha (IL1α) is a cytokine member of the interleukin-1 family. IL-1 consists of two distinct forms: IL1α and IL1β that recognize the same cell surface receptors but are distinct proteins with approximately 25% amino acid sequence identity. IL1α is constitutively produced by epithelial cells and plays an essential role in maintenance of skin barrier function. Upon stimulation, a wide variety of cells including osteoblasts, monocytes, macrophages can be induced to express IL1α. IL1α possesses a wide range of metabolic, physiological, haematopoietic activities, and is critically involved in the regulation of the immune responses and inflammatory responses.